Best Battery Isolator

[Phishin]

I've been reading reviews on various isolators and making sure I'm on top of the latest technologies..... But I value BITOG opinions, and I'm asking for it now.

In my 2018 Silverado 3500HD, I have the heavy duty 220 amp alternator that comes with the snow plow prep package. I'm wanting to install a secondary battery to run peripherals and give me peace of mind.

Although not critically important, I'd also like to be able to "combine" both batteries if my starting battery is dead or weak and I need to get the truck started.

What specific product do you recommend??

 

[wrcsixeight]

https://www.amazon.com/Cole-Hersee-24213-Continuous-Solenoid/dp/B005K2429I

For best possible recharging of accessory battery, Hook it right to alternator via 4AWG or thicker. Use a large ANL fuse close to secondary battery + terminal. If you groud accessory battery to frame, make sure the connection is solid, and then add a frame to alternator ground. I prefer to avoid extra frame grounds as they becomme problematic all too soon and too often.

If you hook Accessory battery to engine battery with solenoid switching, then both sides of the cable should be fused close to battery. You might want to thicken up or add a parallel circuit from alternator to engine battery.

Don't cheap out on the cables or the ring terminals. genuinedealz.com will make custom cables professionally, meaning no Hammer crimps or copper clad aluminum wire.

Triggering the soleoid can be done automatically, or manually or automatic with a manual override.

The Ideal trigger circuit would activate solenoid only after engine is running.

Avoid diode based 'isolators' they drop too much voltage slowing recharging greatly.

YOu can also use a simple On off Switch like Blue seas. 300 amp continuous rating.

https://www.bluesea.com/products/6004/Single_Circuit_ON-OFF_with_Locking_Key_-_Red

There are dozens of different products which can do what you want.
I use a Blueseas 6007m manual switch myself

 

[SnowDrifter]

Why do you feel that you need a battery isolator for this application?

 

[Donald]

Originally Posted by Phishin
I've been reading reviews on various isolators and making sure I'm on top of the latest technologies..... But I value BITOG opinions, and I'm asking for it now.

In my 2018 Silverado 3500HD, I have the heavy duty 220 amp alternator that comes with the snow plow prep package. I'm wanting to install a secondary battery to run peripherals and give me peace of mind.

Although not critically important, I'd also like to be able to "combine" both batteries if my starting battery is dead or weak and I need to get the truck started.

What specific product do you recommend??


A battery isolator is commonly used in boat to isolate the "house" load from the starting load. You do not want your refrig to drain the battery needed to start the boat for example. A battery switch is used when you want to be able to combine batteries for starting. The isolator is basically a silicon diode to allow the electricity to flow one way, from the alternator to battery. It will impose a 0.7V drop. There are also battery combiners that sense the alternator is running and then combine two batteries. Isolated when engine is off.
Only a switch would allow the batteries to be combined for starting. This is the way they are typically used on boats.

 

[WyrTwister]

Were it me , I would use a starter solenoid .

https://www.google.com/search?q=starter+solinoid&ie=utf-8&oe=utf-8&client=firefox-b-1

 

[Phishin]

Originally Posted by wrcsixeight
https://www.amazon.com/Cole-Hersee-24213-Continuous-Solenoid/dp/B005K2429I

For best possible recharging of accessory battery, Hook it right to alternator via 4AWG or thicker. Use a large ANL fuse close to secondary battery + terminal. If you groud accessory battery to frame, make sure the connection is solid, and then add a frame to alternator ground. I prefer to avoid extra frame grounds as they becomme problematic all too soon and too often.

If you hook Accessory battery to engine battery with solenoid switching, then both sides of the cable should be fused close to battery. You might want to thicken up or add a parallel circuit from alternator to engine battery.

Don't cheap out on the cables or the ring terminals. genuinedealz.com will make custom cables professionally, meaning no Hammer crimps or copper clad aluminum wire.

Triggering the soleoid can be done automatically, or manually or automatic with a manual override.

The Ideal trigger circuit would activate solenoid only after engine is running.

Avoid diode based 'isolators' they drop too much voltage slowing recharging greatly.

YOu can also use a simple On off Switch like Blue seas. 300 amp continuous rating.

https://www.bluesea.com/products/6004/Single_Circuit_ON-OFF_with_Locking_Key_-_Red

There are dozens of different products which can do what you want.
I use a Blueseas 6007m manual switch myself


There are "smart" solenoids that isolate the batteries until the car is running. And only when the starting battery is up to say 12.5 volts (charged ENOUGH to re-start the engine), will it close the loop and then allow the auxillary battery to be charged. This is always giving the starting battery priority.

They also monitor each battery's voltage and if one is draining, it will isolate the two batteries protecting one of them from being depleted.

Here is what I'm looking at:
https://www.amazon.com/Cole-Hersee-48530-Battery-Isolator/dp/B00LMGPHW2

From Product Description:
Prevents loads on auxiliary battery from draining the starting battery.
It works with all types of alternator.
Smaller and lighter than traditional isolators.
There are no efficiency losses due to diodes. It allows bi-directional charging from the alternator or from shore power.
It reduces the load on the charging system by not connecting the auxiliary battery until the primary battery is charged to 13.2V.

 

[Phishin]

Originally Posted by SnowDrifter
Why do you feel that you need a battery isolator for this application?


My desire is to have some extra things run off the auxiliary battery. Things like an air compressor, extra lights, possibly a power inverter, etc. etc. I could put a nice deep cycle battery under the hood (the truck already has a tray for it) and let this battery take the drain/draw of these extra items without possibly draining my main starting battery.

 

[SnowDrifter]

Originally Posted by Phishin
Originally Posted by SnowDrifter
Why do you feel that you need a battery isolator for this application?


My desire is to have some extra things run off the auxiliary battery. Things like an air compressor, extra lights, possibly a power inverter, etc. etc. I could put a nice deep cycle battery under the hood (the truck already has a tray for it) and let this battery take the drain/draw of these extra items without possibly draining my main starting battery.

If you plan to run these with the vehicle off, then this is a good situation for an isolator

If you will have the truck running, then there's no point and it introduces a failure point


There are 2 types of isolaters

Relay based

And diode based

Diode based tends to be more robust, easier to install, but comes at the expense of efficiency. Diodes have a 0.7v drop on them and take some considerations in regard to cooling and alternator charge voltage

Relay based requires you installing a trigger wire, has moving parts



Diode based: https://www.amazon.com/NOCO-IGD200HP-200A-Battery-Isolator/dp/B00316GNYM/

Relay based: https://www.amazon.com/Stinger-SGP32-Battery-Relay-Isolator/dp/B001HBYXVS/


Also: It would be good to invest in a battery charger for this application. Alternators aren't meant for charging batteries

 

[Phishin]

Originally Posted by SnowDrifter

If you will have the truck running, then there's no point and it introduces a failure point


You see no harm if I occasionally draw some decent amps from both batteries if they were simply ran in parallel with the truck running?

My thought was if I had a Deka AGM Deep Cycle as my auxiliary battery, I could isolate the high amp draws to this battery only, and thus "protect" my starting battery.

I think just simply hooking them in parallel is a bad idea, right? If one battery goes bad, they will both go bad. And if both get drained, it's going to tax the heck out of my alternator.

How would you wire your truck if this was yours?

 

[SnowDrifter]

If it were mine...

If I intended to leave the truck off while running accessories, I'd install a group 31 deep cycle battery and use that to run accessories and install a relay isolator on a manual switch. Charge the battery at home with an external charger overnight. The isolator will be there as a backup in case I drain the battery halfway through a job, but I wouldn't rely on the alternator to charge a drained battery as 1. alterantors aren't designed to cope with the 100% duty cycle of charging batteries, and 2. an alternator doesn't do a great job of charging a deeply discharged battery - a process which takes several hours


If I wanted to leave the truck on, it depends... If I'm not running a ton of things, I'd forego the extra battery altogether and install a larger alternator from Mechman or DC power along with 0 gauge upgrades to the alternator ground, battery ground, and alternator charge wire. If I need intermittent power output in excess of what the alternator could supply, I'd do the same but with a second battery in parallel. No isolator. If I needed continuously more power than a single alternator could supply, I'd install a second alternator with a second battery, all in parallel, no isolator.

In all cases, I'd install a digital voltage gauge



Background: Running high power draw setups on personal vehicles that need to be reliable enough to be reliable on a daily driver. Think around 1400 amps DC current draw